Optical signals are usable for data transmission between optical devices. Optical signal transmitters and/or receivers are often fabricated in one type of integrated circuit (IC) chip, such as those using semiconductor substrates primarily made of class III-V semiconductor compound, while signal processor ICs controlling the optical signal transmitters and/or receivers often employ a second type of IC chip, such as those using semiconductor substrates primarily made of silicon (Si). Devices, such as optical devices, employing heterogeneous ICs of different types are useful. However, conductive connection between different types of ICs in a conventional multi-chip module often employs either wire bonding or flip-chip bonding. For wire bonding, the conventional multi-chip module is large and signal speeds are limited. For flip-chip bonding used in a conventional multi-chip module, due to different contact pad metals such as gold (Au) or aluminum/copper (Al/Cu) pads, two different bump formation processes such as gold-gold (Au—Au), gold-tin (Au—Sn), and/or tin silver/silver tin copper (SnAg/SnAgCu) are used. These solder bump formation processes in flip-chip bonding add cost and reduce overall yield.